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Frontispiece: Surface Segregated AgAu Tadpole‐Shaped Nanoparticles Synthesized Via a Single Step Combined Galvanic and Citrate Reduction Reaction
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Thayana da C. Alves Mariele R. S. Gonçalves Francyne C. S. Correia Virgínia C. da Silva Paulo T. de Sousa Jr. Mário G. de Carvalho Raimundo Braz‐Filho Evandro L. Dall'Oglio 《Helvetica chimica acta》2014,97(11):1469-1474
From the hexane and MeOH extracts of Annona coriacea Mart . (Annonaceae) seeds, two novel acetogenins, coriapentocins A and B ( 1 and 2 , resp.) were isolated. The known acetogenin bullacin ( 3 ) was also isolated from the hexane extract. The structures of compounds 1 – 3 were elucidated by NMR and MS analysis, and relative configurations were established by comparison with literature data. 相似文献
176.
Xerardo García-Mera José E. Rodríguez-Borges M. Luísa C. ValeMaria J. Alves 《Tetrahedron》2011,67(37):7162-7172
The cycloaddition between protonated glyoxylate imines possessing two chiral auxiliaries, N-(S)- or N-(R)-1-phenylethyl and (−)-8-phenylmenthyl or (+)-8-phenylneomenthyl, and cyclopentadiene is described. The absolute configuration of all adducts formed was unequivocally assigned through NMR, specific optical rotation, and X-ray data of appropriated derivatives. Experimental results confirm the highly exo-selectivity for these aza-Diels-Alder reactions, single adducts being obtained from combinations of (8PM)-(R-PEA) and (8PNM)-(S-PEA). 相似文献
177.
Sofia Nikolaou Sérgio Hiroshi Toma Vagner Roberto de Souza Juliano B. Alves Koiti Araki Henrique Eisi Toma 《Transition Metal Chemistry》2011,36(7):775-783
The triruthenium carboxylate cluster [Ru3O(OAc)6(py)2(bpp)]+ (OAc = acetate) containing the bridging 1,3-bis(4-pyridyl)propane (bpp) ligand, and its dimeric species [{Ru3O(OAc)6(py2)}2(μ-bpp)]2+ were synthesized in order to investigate their inclusion compounds with β-cyclodextrin (β-CD). Characterization of the complexes
was carried out based on spectroscopic, electrochemical and spectroelectrochemical techniques, while the formation of inclusion
complexes was evaluated using 1H NMR/NOESY spectroscopy. Since bpp is a flexible ligand, a DFT study was carried out in order to characterize its conformational
isomers and their possible role in the host–guest chemistry with β-CD. Instead of observing the formation of inclusion compounds
with different stoichiometries, we observed the formation of 1:1 bpp/β-CD compounds in which the bpp ligand assumes different
conformations. The assembly of polymetallic rotaxane species was successfully demonstrated by monitoring the 1H NMR spectra of the monomeric cluster species in the presence of aquapentacyanoferrate(II) ions and β-CD. 相似文献
178.
Martins GV Mano JF Alves NM 《Langmuir : the ACS journal of surfaces and colloids》2011,27(13):8415-8423
In this paper, we describe the construction and characteristics of thermoresponsive, thin nanostructured films prepared by layer-by-layer sequential assembly of chitosan-graft-NIPAAm and alginate. FTIR and (1)H NMR spectra have confirmed the introduction of NIPAAm moieties onto the chitosan backbone. The LCST of the synthesized copolymer was found to be around 31-33 °C. The formation of the polyelectrolyte multilayers containing the copolymer and alginate was followed in situ by quartz crystal microbalance with dissipation monitoring technique and ex situ by UV-vis measurements. Our results revealed the linear increase of the multilayer film growth and the influence of the presence of salt. Moreover, AFM analysis has confirmed that PNIPAAm is able to reconform upon temperature swaps even when combined with other layers in a polyelectrolyte multilayer, demonstrating that the nanoassemblies are thermoresponsive. Preliminary results showed that, upon reducing culture temperature below PNIPAAm LCST, a gradual detachment of cell sheets from these PNIPAAm-based coatings has occurred. 相似文献
179.
Leonardo M. PereiraWagner A. Alves 《Vibrational Spectroscopy》2011,56(2):250-254
Raman experiments of formamide and zinc chloride solutions in a wide concentration range (0.1-5.0 mol kg−1) have been carried out. The spectral changes were interpreted on three different ways: (i) the rupture of the H-bonds of FA was evidenced by the trend observed in the νCO, δHNH and restricted (translation or libration) modes; (ii) the appearance of a new band in the νCN region (∼1338 cm−1) was assigned to FA coordinated to Zn (II) through nitrogen atom; (iii) the electronic delocalization in the FA structure upon complexation provided the appearance of new features in the δCH and νCH regions. The quantitative treatment performed at the νCN region of FA allowed the determination of an average number of 3 FA molecules per Zn (II) in the first solvation shell. This value is supported by the appearance of features assigned to ZnCl+ and ZnCl2 entities that also occupy vertices of the tetrahedron at higher salt concentrations. The present study may be useful for a better understanding on electrochemical processes employed in the production of dendritic zinc films as well as FA hydrolysis catalyzed by this metal. 相似文献
180.
de Souza CA Colombo AP Souto RM Silva-Boghossian CM Granjeiro JM Alves GG Rossi AM Rocha-Leão MH 《Colloids and surfaces. B, Biointerfaces》2011,87(2):310-318
The kinetic of chlorhexidine digluconate (CHXDG) uptake from aqueous solution by hydroxyapatite (HA) was investigated by ultraviolet (UV) analysis performed in HA powder (UV-solid) after the CHX adsorption. Adsorption isotherm of chlorhexidine (CHX) uptake was modeled by a combination of Languimir and Langmuir-Freundlich mechanisms. Strong molecule-molecule interactions and positive cooperativity predominated in the surface when CHX concentration was above 8.6 μg(CHX)/mg(HA). UV-solid spectra (shape, intensity and band position) of CHX bound to HA revealed that long-range molecular structures, such as aggregates or micelles, started to be formed at low CHX concentrations (1.52 μg(CHX)/mg(HA)) and predominated at high concentrations. Grazing-incidence X-ray diffraction (GIXRD) analysis from synchrotron radiation discarded the formation of crystalline structures on HA surface or precipitation of CHX crystalline salts, as suggested in previous works. The effect of the HA/CHX association on HA in vitro bioactivity, cytotoxicity and CHX antimicrobial activity was evaluated. It was shown that CHX did not inhibit the precipitation of a poorly crystalline apatite at HA/CHX surface after soaking in simulating body fluid (SBF). Cell viability studies after exposure to extracts of HA and HA/CHX showed that both biomaterials did not present significant in vitro toxicity. Moreover, HA/CHX inhibited Enterococcus faecalis growth for up to 6 days, revealing that binding to HA did not affect antimicrobial activity of CHX and reduced bacterial adhesion. These results suggested that HA/CHX association could result in a potential adjuvant antimicrobial system for clinical use. 相似文献